Question

"Koplik's spots" on the oral mucosa are a pathognomonic sign of which infectious disease?

• A. Rubella
• B. Measles
• C. Chickenpox
• D. Scarlet fever

Hint:

Koplik's spots = \textbf{Measles hallmark}. Seen before rash $\rightarrow$ helps early diagnosis.

Answer 1

The Correct Option is B

Concept: Koplik's spots are small bluish-white spots with a red halo seen on the buccal mucosa (inside the cheeks). They are considered pathognomonic, meaning they are specifically characteristic of a particular disease.

• Measles (Rubeola): Presence of Koplik's spots before the skin rash appears.
• Rubella: Mild rash, no Koplik's spots.
• Chickenpox: Vesicular rash ("dew drops on a rose petal").
• Scarlet fever: Strawberry tongue and rash.

Step 1: Identify the clinical sign.
Koplik's spots appear in the early stage of infection on the oral mucosa.
Step 2: Associate with the disease.
These spots are uniquely associated with measles and appear before the characteristic maculopapular rash.
Step 3: Differentiate from other diseases.
Other infectious diseases may have oral or skin manifestations, but none show Koplik's spots.
Step 4: Conclude the answer.
Thus, Koplik's spots are a pathognomonic sign of measles.